aahn Posted January 14, 2006 Share Posted January 14, 2006 PO171 and PO440 My guess is that this is a problem with the MAF sensor Took it out and the wires "look" dirty but i wouldn't really know what dirty wires look like... It appears to have some kind of build up on the middle of both wires but then again maybe that's how they are suppose to appear... Could this combination of codes also mean i need to replace an O2 sensor? This is for a 2000 RX300 btw Quote Link to comment Share on other sites More sharing options...
mehullica Posted January 15, 2006 Share Posted January 15, 2006 Clean the MAF with electronics parts contact cleaner to fix the po171. Po440 is an EVAP code. Probabaly a loose gas cap. Quote Link to comment Share on other sites More sharing options...
mikey00 Posted January 16, 2006 Share Posted January 16, 2006 PO440 is also caused by the evap hose coming off the metal tube behind the air filter box directly below the brake fluid container. Did you, or someone else, recently check the air filter and cause this when lifting up on the top of the air filter box? Quote Link to comment Share on other sites More sharing options...
AmFam Posted January 16, 2006 Share Posted January 16, 2006 The 170 code also comes up when you have a lean bank issue. Like a vacuum leak for example. What happens is the O2 says it is lean as there is much more air than the normal air to fuel ratio. Since the O2 can not determine anything other than a good or bad mix it trips the code saying it is defective or you have a rich or lean bank. 90 percent of the time there is nothing wrong with the O2. It trips due to the reading it is sending to the ECM/PCM. So do a good look around for a vacuum leak as well.. Quote Link to comment Share on other sites More sharing options...
Rx330driver Posted January 17, 2006 Share Posted January 17, 2006 Im a total noob at cars and i let other people fix things for me, but im just wondering. These sensor warnings you guys are talking about, where do u see them. I mean is there actually a screen on the car that says P0440 error? Quote Link to comment Share on other sites More sharing options...
aahn Posted January 17, 2006 Author Share Posted January 17, 2006 no, just a general check engine light comes on and you use a diagnostic tool to determine what the codes are and what triggers the light. i get mine's lent out for free at an advance auto parts. an update: i cleaned the MAF sensor, the wires were filthy btw with a non-alcoholic electronics cleaner and the light went away. I think the response improved as well. i'll check the evap too thanks for the tip Quote Link to comment Share on other sites More sharing options...
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